Backup tools for backup Linux and Windows systems with encryption

Deja Dup doesn't support full system encryption, only home directory.
rsync - I should make the backup, then archive the folder and then encrypt it. It's too long.
tar archive of the system - I should make tar, and then encrypt the archive. It's too long.
encrypt the external hard drive with cryptsetup and then put tar archive of the system there or use rsync - I can't use the standard Windows utility to make the backup because it requires ntfs.
Am I right? What would you recommend?